IR-S/PDIF Receiver

This simple circuit proves to achieve surprisingly good results when used with the IR–S/PDIF transmitter described elsewhere in this issue. The IR receiver consists of nothing more than a photodiode, a FET and three inverter gates used as amplifiers. The FET is used as an input amplifier and filter, due to its low parasitic capacitance. This allows R1 to have a relatively high resistance, which increases the sensitivity of the receiver. The bandwidth is primarily determined by photodiode D1, and with a value of 2k2 for R1, it is always greater than 20 MHz.